This invention relates to coated papers suitable for gravure printing and to coating compositions used to prepare such coated papers.
The use of rotogravure printing processes in printing high volume, high quality publications such as magazines, catalogues, product brochures and the like is well-known. In such processes, a gravure master is employed which usually has a shape which has a working surface which is generally smooth except for a regular array of tiny, discrete intaglio cell cavities which are excavated to a depth below the working surface. This array of cavities corresponds to the images to be printed on the paper. Ink is applied to the working surface such that the cavities retain significant amounts of the ink below the working surface. The master is then pressed against a paper web, and the ink transfers from the cavities to the paper thereby producing a printed reproduction of the desired image on the paper.
Rotogravure printing, unlike offset printing and letter press printing, is very sensitive to poor ink transfer. For example, missing gravure dots and defective reproduction dots are often noticed by the reader. Thus, a smooth and ink receptive paper is generally required.
The paper used in the rotogravure printing process is normally a coated paper comprising a wood pulp web as the substrate and a coating containing a pigment and a binder, e.g., a natural binder such as starch, a synthetic binder such as a styrene/butadiene latex or a mixture thereof.
Unfortunately, most of the coated papers used in rotogravure printing are either very expensive and/or are not sufficiently smooth and ink receptive to permit the high speed, high quality, printing that is desired in rotogravure printing processes.
Therefore, it is highly desirable to provide a coated paper that is relatively inexpensive which has improved printability in rotogravure processes.